Curious About gameboy4iphone

I recently downloaded the gameboy4iphone emulator from ZodTTD and have run into a little problem. When I opened up the app, a pop-up appeared saying "No ROMs found. Would you like to find them?". I tapped yes, and was directed to a website of which will remain unknown. The website told me that downloading ROMs was perfectly legal if I owned a physical copy of the game (which I do).